The fields of radiology and nuclear medicine typically involve the exposure of a patient to radiation or the introduction of radiation into the patient metabolism or anatomy which can be imaged for diagnostic purposes. Other activities involve theraputic, localized exposure to controlled levels of radiation which is typically intended to affect selected tissue areas.
One of the components of such a radiological system is a collimator which consists of a series of generally parallel, or occasionally converging or diverging channels in the radiation path, the purpose of which is to filter the radiation passing through so as to select radiation only on a predetermined trajectory and within a selected acceptance angle. For example, it is frequently desired to view the radiation from a radioisotope placed in the blood circulatory system at an angle other than orthogonal to the patient's surface. It is additionally desired to detect this radiation as close to the radiation source as possible. For this purpose a collimator having the collimation channels angled at a predetermined angle is applied between the patient skin surface and the radiation detectors as close to the subject area, such as the patient heart, as possible. Collimators to provide this function are known in the art and typically consist of a plurality of generally parallel radiation transmissive channels surrounded by lead wall material. Such collimators are generally hand fabricated at great expense using a corrugated pattern of lead sheet and are thus set at a fixed angle of view. In addition the lead sheet material is normally quite soft making it easy to distort and thus ruin the collimator of such a design.
Such prior art collimators, in addition to being fixed in their slant angle of view, are also fixed in channel length. Channel length in a radiation collimator determines the compromise between collimator resolution, which increases with the channel length to aperture length ratio versus the collimator sensitivity which is reduced with the reduction in acceptance angle that comes from increasing collimator resolution. Thus, in prior art systems, in order to accommodate a range of resolution and sensitivity criteria it has been necessary to possess a number of the expensive prior art design collimators.
One of the recent advances in radiation medicine, tomography or related techniques, involves the use of scanning and imaging radiation equipment. One of the difficulties with this technique is sampling the subject's radiation distribution from an adequate number of view angles.